Historically, markup was used to refer to the process of marking manuscript copy for typesetting with directions for formatting such as use of type fonts and sizes, spacing, indentation, etc. In today's digital age, markup refers to electronic markup, i.e., the internal and sometimes invisible codes in an electronic document that describe the formatting of the document. Generally, a user can view the markup of an electronic document by looking at the source code of the document with the browser displaying the electronic document. The electronic markup of a document generally provides encoding of text as well as details about the structure, appearance and presentation of the text and content in the document.
The markup of an electronic document usually is programmed using a markup language. A markup language provides syntax and procedures for embedding in a document tags that control the formatting of the text when the document is viewed by a special application such as a Web browser. Commonly used electronic markup languages include HTML, XML, and ASP.NET. Traditionally, markup languages are used to design the content and appearance of a static document.
However, for an interactive application such as a Web application, the content and/or presentation of a document such as a Web page may change, for example, based on user input. The markup of the document thus needs to be accompanied by information governing the behavior of the document. Traditionally, document behavior has been implemented procedurally in a script. To provide dynamic document behavior, a markup of the document may call on methods in the script at the appropriate time. The intermingling of markup and calls to script methods thus makes it difficult to independently design the markup for a document. Meanwhile, because a script language traditionally has been procedural and imperative, a user of a document usually cannot use the script language to design a specific behavior for the document.
While specific disadvantages of existing systems have been illustrated and described in this Background Section, those skilled in the art and others will recognize that the subject matter claimed herein is not limited to any specific implementation for solving any or all of the described disadvantages.